Tuesday, May 29, 2018

Carbon monoxide gas forms underground during a mine fire or after an explosion, placing miners in peril. Canaries are more sensitive to the than humans are. After a mine fire or explosion, mine rescuers would descend into the mine, carrying a canary in a cage. If the canary exhibited signs of distress the miners would evacuate before they were affected by the gas. The lives of many miners were saved but the canaries perished. Inventors came up with a humane device that revived the affected birds:

"The circular door of the cage "would be kept open and had a grill to prevent the canary [from] escaping. Once the canary showed signs of carbon monoxide poisoning the door would be closed and a valve opened, allowing oxygen from the tank on top to be released and revive the canary."

This practice continued for almost 100 years, until birds were replaced by technology in 1986.